It is known to treat patients for decubitus ulcers, bed sores, etc. with a mattress having alternatingly inflatable structures on the mattress for providing alternating support areas for the patient. Some of these mattresses include holes in a top of the mattress for venting a portion of the inflating gas, such as air, to further treat the patient. Examples of such mattresses are described in the following U.S. Pat. Nos.: Armstrong, 2,998,817; Glass, 3,467,081; Lapidus 3,653,083; and Tringali et al., 4,197,837, all of which have ventilating openings. Examples of patient treating pads without ventilation openings are described in the following U.S. Pat. Nos.: Bates et al., 2,896,612; Grant, 3,199,124; and Whitney 3,701,173.
A major problem with prior patient treatment mattresses on the market which had alternatingly inflatable structures was their tendency to "crawl" during use. This crawling was also aggravated by movement of the patient upon the mattress. Some such mattresses after a period of time were found to be sticking out the side of the patient's bed with the patients almost being unsupported by the treatment mattress. The reason for this problem is not fully understood, but it is believed that the sequential inflation and deflation of portions of the mattress acts somewhat like raising and lowering alternating feet of a multi-legged caterpillar or worm causing such caterpillar to "crawl." The exposed surface of these mattresses were usually of a thermoplastic film material, and the outer surface of such thermoplastic film may also contribute to a very small, almost imperceptible sliding motion of the inflated structures on the mattress during each inflation and deflation cycle.
To overcome the "crawling" problem, the manufacturers of alternatingly inflatable patient support mattresses have utilized expensive, full width end extensions of the mattresses, such as shown at 16 in Grant, U.S. Pat. No. 3,199,124, for folding over and tucking under the complete width of a conventional mattress upon which the patient treatment mattress rests. Such end extensions, which have been made of a very thick plastic material for firm control, cause the patient treating mattress to be very expensive, thus necessitating the recleaning of the mattress for use with many different patients. Current mattresses on the market cannot be economically disposed of after a single patient use as is highly desirable to reduce the chance of cross-contamination between patients.
It should be noted that different kind of pads, such as shown in the Gammons et al. U.S. Pat. No. 4,149,541, do not have the "crawl" problem because they do not alternately inflate different passages. Instead, such pads are continuously inflated with a circulating liquid and there is no sequential inflation and deflation of adjoining sections. A fabric layer on such continuously inflated pads is primarily for comfort at patient's skin contact or for retaining a liquid on the surface for hot or cold liquid therapy.